1. Field of the Invention
The present invention relates to an optical function device, and more particularly, to a new optical function device which is capable of executing logical operation and optical amplification of optical signal as well as image optical signal and is capable of being operated in a wide temperature range, and thus can be used preferably in optical electronics such as optical communication, optical image processing or optical computer capable of high-level information processing.
2. Description of the Related Art
In an optical communication of recent years, an optical signal is amplified by using an erbium-doped fiber or a crystal, and the optical signal is transferred over a long distance without any electric amplifier, thereby carrying out a high-level information transmission.
On the other hand, there has been developed an optical element for inverting an optical signal by using the negative nonlinear absorption effect of erbium ions (for example, see xe2x80x9cAll-optical inverter operating over a temperature range of 15-1400K in erbium-doped lutetium aluminum garnetxe2x80x9d, by Yoshinobu Maeda, Applied Physics Letters, Volume 72, pp395-397).
However, the conventional erbium-doped fiber or crystal has no function of optical operation of an optical signal. The conventional optical element using the negative nonlinear absorption (NNA) has no function or effect of optical amplification of an optical signal. In addition, there has not been developed, for an optical communication wavelength band (1.5 xcexcm), any optical element capable of controlling an image optical signal directly by another image optical signal and operable in low to high temperatures.
In view of the foregoing, it is the main object of the present invention to provide a new optical function device which is capable of inverting and amplifying an optical signal of the optical communication wavelength band, and executing operation of an image optical signal, and is operable in a wide temperature range.
The above and other objects, advantages and features of the present invention are accomplished by a optical function device. An optical function device composed of a light transmitting medium containing a rare earth element, comprising a portion thereof doped with 1xc3x971023 per 1 m3 or more of the rare earth element for executing an inversion of an optical signal, a portion thereof doped with 1xc3x971021 per 1 m3 or more of the rare earth element for executing an amplification of the optical signal with an excitation light superposed thereto.
In a further aspect of the invention, the rare earth element is Er (erbium), a wavelength of the optical signal falls in a range of 1.5 xcexcm xcx9c1.6 xcexcm, and a wavelength of the excitation light is 0.98 xcexcm band or 1.48 xcexcm band or 0.8 xcexcm band.
In another aspect of the present invention, said optical function device is operated in a temperature range of at least xe2x88x92100xc2x0 C. xcx9c300xc2x0 C.